1. Here's the cafeteria of our school.
2. Here's the cafeteria in our school.
3. Here's the cafeteria at our school.
[Which preposition do we have to use? Are all possible?]
4. This is the cafeteria of our school.
5. This is the cafeteria in our school.
6. This is the cafeteria at our school.
[Which preposition do we have to use? Are all possible?]